| 69 | |
| 70 | |
| 71 | class Encryptor(object): |
| 72 | def __init__(self, password, method): |
| 73 | self.password = password |
| 74 | self.key = None |
| 75 | self.method = method |
| 76 | self.iv_sent = False |
| 77 | self.cipher_iv = b'' |
| 78 | self.decipher = None |
| 79 | self.decipher_iv = None |
| 80 | method = method.lower() |
| 81 | self._method_info = self.get_method_info(method) |
| 82 | if self._method_info: |
| 83 | self.cipher = self.get_cipher(password, method, 1, |
| 84 | random_string(self._method_info[1])) |
| 85 | else: |
| 86 | logging.error('method %s not supported' % method) |
| 87 | sys.exit(1) |
| 88 | |
| 89 | def get_method_info(self, method): |
| 90 | method = method.lower() |
| 91 | m = method_supported.get(method) |
| 92 | return m |
| 93 | |
| 94 | def iv_len(self): |
| 95 | return len(self.cipher_iv) |
| 96 | |
| 97 | def get_cipher(self, password, method, op, iv): |
| 98 | password = common.to_bytes(password) |
| 99 | m = self._method_info |
| 100 | if m[0] > 0: |
| 101 | key, iv_ = EVP_BytesToKey(password, m[0], m[1]) |
| 102 | else: |
| 103 | # key_length == 0 indicates we should use the key directly |
| 104 | key, iv = password, b'' |
| 105 | self.key = key |
| 106 | iv = iv[:m[1]] |
| 107 | if op == 1: |
| 108 | # this iv is for cipher not decipher |
| 109 | self.cipher_iv = iv[:m[1]] |
| 110 | return m[2](method, key, iv, op) |
| 111 | |
| 112 | def encrypt(self, buf): |
| 113 | if len(buf) == 0: |
| 114 | return buf |
| 115 | if self.iv_sent: |
| 116 | return self.cipher.update(buf) |
| 117 | else: |
| 118 | self.iv_sent = True |
| 119 | return self.cipher_iv + self.cipher.update(buf) |
| 120 | |
| 121 | def decrypt(self, buf): |
| 122 | if len(buf) == 0: |
| 123 | return buf |
| 124 | if self.decipher is None: |
| 125 | decipher_iv_len = self._method_info[1] |
| 126 | decipher_iv = buf[:decipher_iv_len] |
| 127 | self.decipher_iv = decipher_iv |
| 128 | self.decipher = self.get_cipher(self.password, self.method, 0, |
no outgoing calls